Help about failed to load ...

The code I use Ncover to test has already pass the nant test.

but when I use nant call ncoverreport. It failed.

there are many Message like this:

MESSAGE: Failed to load symbols for module [nunit.framework.dll] in [c:\windows\assembly\gac\nunit.framework\2.1.4.0__96d09a1eb7f44a77].

......

and It is failed....

but acturlly, the nunit.framework.dll is exists.

For I just a beginner,So I have no idea,Is there anyone can help me ?